There is a constant need for precisely controlled pretilt angles in a liquid crystal cell. Sometimes the pretilt angles needed for certain applications can be quite large and are difficult to reliably obtain using conventional alignment techniques.
U.S. Patent Application Publication No. 2005/0260426 to Kwok teaches a technique for generating a large controllable pretilt angle using inhomogeneous alignment surfaces. Instead of being uniform and composed of a single material, the alignment surface includes nano and micro-scale domains of different alignment materials. In particular, if the alignment materials are such that one kind is capable of generating a vertical alignment and the other kind is capable of generating a homogeneous or horizontal alignment, then the resultant surface generates an intermediate pretilt angle.
Kwok's published application applies random phase segregation upon drying of a binary mixture of different alignment materials. The distribution of domains is random, sometimes not uniform, and is difficult to control. Therefore, it is desired to fabricate an inhomogeneous alignment surface that is highly controllable and to generate a uniform alignment layer for large substrates.